[프로그래머스] Lv.2 택배상자

 

[문제]

https://school.programmers.co.kr/learn/courses/30/lessons/131704

프로그래머스

 

 

[소스 코드]

import java.util.*;
class Solution {
    public int solution(int[] order) {
        int answer = 0;
        int n = order.length;
        int idx = 0;
        Stack<Integer> stack = new Stack<>();
        for(int i=1;i<=n;i++){
            stack.push(i);
            while(!stack.isEmpty() && stack.peek()==order[idx]){
                stack.pop();
                idx++;
                answer++;
            }
        }
        return answer;
    }
}